Couches throughout the nation have become notorious for containing flame-retardant chemicals that may do more harm than good.

Now, it turns out, those chemicals may also be leaching from the walls that surround you.

Because of laws passed in the 1970s, many homes and workplaces built in the United States since then contain foam insulation doused with flame retardants.

Not only are these substances potentially hazardous, but they also often do not make a structure any safer from fire, say researchers from UC Berkeley, Lawrence Berkeley National Laboratory and other institutions, in a study published in November.

Inspired by their findings, a Bay Area lawmaker recently said she plans to introduce a bill in the Legislature that would reduce flame retardants in foam insulation installed anywhere in California. At the same time, California is revising a decades-old flammability standard in order to curb use of flame retardants in furniture. A proposal is expected by the spring.

The flame retardants used most in building materials either are known to be dangerous or have had red flags raised about their safety. The tens of millions of pounds made annually can enter the environment, possibly by leaching through cracks, experts say.

'Potential to harm'

"You do find these chemicals in dust and in people," said Arlene Blum, a co-author of the report, a visiting scholar at UC Berkeley and executive director of the Green Science Policy Institute, a health watchdog group in Berkeley. They have "the potential to harm our health and environment," she said.

Foam insulation came into widespread use half a century ago to make buildings more energy-efficient. Since the 1970s, U.S. building codes have required the insulation to be protected from fire in two ways, according to researchers.

A thick wallboard - also known as a thermal barrier - has to separate the interior of a room from the insulation to keep a fire away from the material for at least 15 minutes.

Insulation is also required to pass the Steiner Tunnel test. In the test, a piece of material is placed on the ceiling of a long tunnel, exposed to a flame from one end of the tunnel and tracked to measure how quickly flames burn through it.

Manufacturers have never been requiredto include flame retardants in their products, but have typically used them to pass the Steiner Tunnel test, according to the study, which appeared in the journal Building Research and Information.

Unforeseen effects

In the 1970s, "People were worried about fire and came up with standards they thought would help," Blum said. "They thought, 'It must be good to have flame retardants. It'll be better.' They didn't check carefully to see if there was a benefit. They didn't think to see the adverse impacts of the chemicals being used to meet the standards."

The two most commonly used flame retardants in foam plastic insulation are HBCD and TCPP, both of which can enter the environment and be inhaled or ingested because they are not chemically bonded to the insulation, researchers said.

About 62 million pounds of HBCD are produced annually worldwide, according to a United Nations committee, and 90 percent of it is added to polystyrene insulation. HBCD has been shown in animal studies to disrupt hormones and harm the developing nervous system, and it has been found in human breast milk, fat and blood. Citing health concerns, the European Union plans to phase it out by 2015.

TCPP is used in most polyurethane and polyisocyanurate insulations, and 80 million pounds of it was produced worldwide in 1997. Its health effects are little known, but it is considered a potential carcinogen because it is similar to other compounds known to cause cancer.

Altogether, Blum estimates that these chemicals have ended up in hundreds of thousands of buildings in the United States. But their fire-safety effects are essentially rendered moot, because, as required by law, the insulation is already protected by the thermal barrier, researchers contend. Removing the flame retardants would not make the insulation more susceptible to fire.

Ineffective in studies

Studies have even shown that flame retardants don't greatly reduce fire risk when foam plastic insulation is exposed to the interior of a room, with the thermal barrier missing.

"I can't blame manufacturers for originally putting these chemicals in their products," he said. "But once they were in there, getting them out is pretty hard to do, because now the building codes mandate ... certain performance criteria on fire safety testing."

Kathryn St. John, a spokeswoman for the American Chemistry Council, a trade group for the chemical industry, said flame retardants in building materials "provide individuals with fire safety protection and critical escape time should a fire start."

Assemblywoman Nancy Skinner, D-Berkeley, is siding with Blum's team. She said she intends to introduce a bill calling for a reduction in the flame retardants used in insulation.

Shift in public opinion

The powerful chemical lobby has helped kill all recent attempts to regulate flame retardants in California, but Skinner believes that public opinion has shifted. She noted Gov. Jerry Brown's effort to revise California's flammability law for furniture by cutting out flame retardants.

The scientists behind the study are calling for their findings to be incorporated into the international residential building codes, which are used by almost every state. The codes are currently being updated, a process that happens every three years.